“Friends” fans noticed Jennifer Aniston’s stand-in was mistakenly featured on camera in two scenes. It took them a decade to find the error, but now they can’t “unsee” it.

A fan spotted the error in Season 9, Episode 15, titled “The One With The Mugging,” and the discovery has since gone viral. The video clearly shows Jennifer Aniston in the role of Rachel Green, standing next to Joey, played by Matthew LeBlanc. As the camera pans away, a woman with completely different features was standing in for Aniston and completely visible on-camera.

Fans from all over the world are joining the conversation and are in complete disbelief that the error slipped past all levels of production and editing.

“The One With The Mugging” is now being called “The One With Fake Rachel.”

Fans are now eagle-eyed while watching the show, and it has since been noted this isn’t the only time this type of mistake happened on the show.

Season 9, Episode 4 also contains a mistake of the same nature. Aniston is featured in the majority of the show but is replaced by a stand-in actress at the 12-minute and 20-second mark in the episode. (RELATED: ‘Far Too Divided’: Jennifer Aniston Slams People Offended By ‘Friends’)

The video clip of the iconic sitcom shows Monica, played by Courteney Cox, and Rachel sitting at a table when Joey walks in to chat with them. Rachel wore a yellow shirt and her hair was curly in the original shot, yet somehow, when the camera shifted to Monica, another woman was visible, and it wasn’t Aniston that was standing by her side.

The stand-in can be seen in a blue top and sporting straight hair.

Aniston hasn’t commented publicly about her replacement getting some air-time.